Prognostic factors for hypotensive effects of isopropyl unoprostone in eyes with primary open-angle glaucoma

It has been reported that isopropyl unoprostone, a prostaglandin-related compound, has potent effects in lowering intraocular pressure and that its hypotensive effect is an increase of uveoscleral outflow. In the present study, we investigated the clinical characteristics of the hypotensive effects of this novel antiglaucoma drug in 115 primary open-angle glaucoma (POAG) eyes. The mean intraocular pressure (+/- standard deviation) before the addition of isopropyl unoprostone to the current regimens was 21.3 +/- 4.4 mmHg. The values at 1 month, 3 months, and 6 months after treatment were, respectively, 20.2 +/- 3.9 mmHg, 19.4 +/- 3.4 mmHg, and 18.4 +/- 2.5 mmHg. In POAG, the outflow pressure difference (delta OP), which is determined as (pretreatment pressure - posttreatment pressure)/(pretreatment pressure - 10) x 100 (%), was reduced by more than 20% in 36 (31%) of 115 eyes, 35 (36%) of 97 eyes, and 33 (53%) of 62 eyes, respectively at 1, 3, and 6 months. We defined the "early success" group as eyes with a significant reduction in delta OP (> or = 20%) at 1-month posttreatment. To identify the prognostic factors related to the significant reduction in intraocular pressure occurring after the administration of this drug, we carried out a statistical analysis by logistic regression analysis. Statistical analysis revealed significant prognostic factors: history of cataract surgery (P = 0.0084) and pretreatment pressure levels (P = 0.0105) at 1-month posttreatment. Also, further statistical analysis showed a significant influence of pretreatment pressure levels (P = 0.0010) at 3 months posttreatment. Our study shows an interindividual difference in the responsiveness of hypotensive effects on POAG eyes and some prognostic factors (history of cataract surgery and pretreatment pressure levels) prior to the use of this drug.